The QUBIC experiment

QUBICQU Bolometric Interferometer for Cosmology

The QUBIC experimentthe Q U Bolometric Interferometer for Cosmology

…for the QUBIC collaboration Elia Stefano Battistelli Sapienza, University of Rome


What is QUBIC?

mm interferometric experiments to observe the Cosmic Microwave Background Radiation Polarization

B-mode RAdiation INterferometer

Q andUBolometric Interferometer for Cosmology

+ =Millimeter-wave Bolometric Interferometer

• The QUBIC collaboration, 2011, APP, 34, 705-716• Piat et al, 2012, JLTP 167, 872P• Ghbri et al, 2014, JLTP 176, 698QUBIC


IT FR

US IN UK IR

QUBIC collaboration

+ NIKHEF, Amsterdamabout to join QUBIC


IT FR

QUBIC collaboration

US IN UK IR



IT FR

QUBIC collaboration

US IN UK IR



Concordia Station: Dome C

123° 23' 42"E, 75° 06' 06" S, 3233m asl


QUBIC Site: Dome CGreat landscape

Healthy weather

Great Base

Great Infrastructures


QUBIC Site: Dome CGreat landscape

Healthy weather

Courtesy L. Valenziano

PWV

(m

m)

0

1Great for CMB observations !

Courtesy of L. Valenziano

Great Base

Great Infrastructures


BRAIN: site testing • Spinelli,, et al., MNRAS, 414, 3272S, 2011• E. Battistelli et al., MNRAS 423, 1293, 2012

!"#$"%#&''"(#)*+*%$#,-#.,%/#

0*(0&)1(#1-2#)*-"1(#

',)1(*314,-#5(,+#

1%+,$'/"("#

#####67869:;8#<=:;87>;?7=@#A#BCDE#F#:7@G;8#<=:;87>;?7=@#A#BCDD#F#

!"#$$%&'('

!"#$$%&')'

!"#*-5"(("2#A<!HI#),J"(#%/1-#BCK++#2&(*-L#$&++"(#.&%#%/*$#*$#1#2*("0%#DMBNO3#+"1$&("+"-%#

2009-2010 campaign was dedicated to mm atmospheric emission and polarization: this was done at 150GHz

! = 0.050± 0.003± 0.011


BRAIN: site testing

2009-2010 campaign was dedicated to mm atmospheric emission and polarization: this was done at 150GHz

• Spinelli,, et al., MNRAS, 414, 3272S, 2011• E. Battistelli et al., MNRAS 423, 1293, 2012

!"#$"%#&''"(#)*+*%$#,-#.,%/#0*(0&)1(#1-2#)*-"1(#',)1(*314,-#5(,+#1%+,$'/"("#

!"#$$%&'('

!"#$$%&')'

! = 0.050± 0.003± 0.011

!"#*-5"(("2#A<!HI#),J"(#%/1-#BCK++#2&(*-L#$&++"(#.&%#%/*$#*$#1#2*("0%#DMBNO3#+"1$&("+"-%#

#####67869:;8#<=:;87>;?7=@#A#BCDE#F#:7@G;8#<=:;87>;?7=@#A#BCDD#F#


Good sensitivity

Good controlof systematics

Both

Possible instruments•  Imagers with bolometers (thermal):

•  No doubt they are nice detectors for CMB: •  wide band•  low noise

•  Interferometers (coherent):•  Long history in CMB

•  CMB anisotropies in the late 90s (CAT, VSA, CBI…•  CMB polarization 1st detection (DASI, CBI)

•  Clean systematics:•  No telescope (lower ground-pickup & cross-polarization)•  Angular resolution set by receivers geometry (well known)

•  Technology used so far•  Antennas + HEMTs : higher noise wrt bolometers

•  Can these two nice devices be combined ?•  Bolometric Interferometry !


Possible configuration

•  In an interferometer, radiation is selected by diffractive apertures and then recombined

•  QUBIC is an adding interferometer: we use the Fizeau approach in which all the outputs are summed (linear combination) into the detector array. Better when there are several apertures.

•  Phase difference is present both before and after the incoming antennas: External phase difference gives the relation visibility FT sky-image…similarly does the internal phase difference but FT-1

•  Thus a Fizeau combination enables imaging in an interferometer except that images are modulated by synthesized beam produced by interference pattern

•  Horns act as diffractive apertures and make a “spatial filtering”: QUIBC is an imager that accept only a sub-set of modes


QUBIC in a nutshell

•  Bolometric interferometer: adding interferometer (synthetic imager) to use the sensitivity of bolometers and the systematic control of interferometers

•  To be installed in Dome C: probably the best place on earth (like Carlsberg beer)

•  ~1.5% of the cleanest sky mapped multifrequency with HWP polarization capability

•  Angular resolution: a little difficult for an interferometer…let’s say 0.5°

•  1st module December 2016 with 2000 TES at 150GHz and 220GHz: goal r<0.05 at 90% C.L.: anticipated sensitivity:

-3.7uK/arcmin @ 150GHz -9.8uK/arcmin @ 220GHz

•  Extended: 6 modules, at 90, 150, 220GHz possibly with KID detectors: goal r<0.01 at 90% C.L….it will require a deep rethinking of Dome C


<1K

300 mK

4K

Cryostat

Sky45 cm

4K

X polarization bolometer array (~30x30)

Filters

Primary horns

Secondary horns

Switches

Half-wave plate

Y polarization bolometer array

(~30x30)

Polarizing grid

<1K

4K4K

4K

QUBIC design

1 horn open

1 baseline

1 baseline

1 baseline

total signal(all baselines)

fringes successfuly observed in 2009 with MBI-4 [Timbie et al. 2006]

1 & 2

2 & 3

2 & 4

MBI-4 data2009 campaign (PBO- Wisc.)

1 & 3

150 GHz20x20 horns14 deg. FWHM

Cold box


Dual Band QUBIC (150/220 GHz in the first module)

•  B2B horns are: -single moded at 150GHz -multi- (few-) moded at 220GHz they are diffractive apertures that make spatial filtering i.e. the entrance pupil is a square array of gaussian-illuminated apertures

•  The beam combiner alone can be used as a telescope (uniformly illuminated pupil) with N~FOV/(λ/D) independent Airy spots

•  On a given focal plane pixel, the synthetic image is the convolution of sky signal (Q,U) and synthetic beam


B.I. = Synthesized imager

20x20 horns 14 deg. FWHM, D=1.2 cm

Primary horns array Synthesized beam

(including detector finite size and 30% BW)

8.5 deg.

FWHM0.54 deg.

Synthesized beam used to scan the sky as with an imager


20x20 horns 14 deg. FWHM, D=1.2 cm

Primary horns array Synthesized beam

Synthesized beam used to scan the sky as with an imager

B.I. = Synthesized imagerAc

know

ledg

men

ts to

P. C

hani

al

(including detector finite size and 30% BW)

8.5 deg.

FWHM0.54 deg.


Systematics: Self-Calibration

Redundant baselines : same Fourier Mode

An active source will be used disentangle different systematics and departure from idealities

•  BI relies on the accurate knowledge of your instrument including the departure from idealities

•  A unique possibility to do that, and to handle systematic errors, is the self-calibration

•  Use horn array redundancy to calibrate systematics•  In a perfect instrument redundant baselines should see the same signal•  Differences due to systematics•  Allow to fit systematics with an external source on the field

Example: exact horns locations (figure exaggerated !!)


Systematics: Self-Calibration

Redundant baselines : same Fourier Mode

•  BI relies on the accurate knowledge of your instrument including the departure from idealities

•  A unique possibility to do that, and to handle systematic errors, is the self-calibration

•  Use horn array redundancy to calibrate systematics•  In a perfect instrument redundant baselines should see the same signal•  Differences due to systematics•  Allow to fit systematics with an external source on the field

Example: exact horns locations (figure exaggerated !!)

An active source will be used disentangle different systematics and departure from idealities


Self-Calibration results

[Bigot-Sazy et al., A&A 2012, arXiv:1209.4905]

Expected signal

(r=0.05)

E!B leakage due to instrum. systematics

residual E!B leakage

Self-Calibration


Dielectrically embedded mesh HWPCardiff, G. Pisano et al. 2012

THE INSTRUMENT

400 primary horns, aluminum platelet FWHM = 14°

Milano Courtesy of F. CavaliereElectro-magnetic switches mainly used for self-calibrationMilano Bibocca, APC, Paris

Off-Axis Gregorian System, 300mm

equivalent focal length, 0.5m mirrors,

Low aberrations (Maynhoot, Rome)


THE INSTRUMENT

Subsystem TemperatureHWP 3 K

Polarizing grid 3 KHorn Arrays 3 K

Primary mirror 1 KSecondary Mirror 1 KDetector arrays 0.3 K

Read out electronics 1 K and 40 K

Dry cryostat with G10 truss Sapienza (Schillaci-Masi)

Ackn

owle

dgm

ents

to C

. Cha

pero

n


THE INSTRUMENT

M. Piat – APC, Marnieros - CNSNM

•  -TES + SQUIDs + SiGe ASIC Mux

•  -2 arrays of 992 NbSi TES

•  -Capacity coupling-Time Domain Multiplexing

•  -Bias reversal AC SQ1 bias

•  -The current bias steps through the rows for a first

multiplexing stage and a cryogenic amplifier steps

through the columns for a second multiplexing stage

•  -This is done by the ASIC

•  -Multiplexing factor 128/1 in a 2D configuration


THE INSTRUMENT

M. Piat – APC, Prele - APC

•  -TES + SQUIDs + SiGe ASIC Mux

•  -2 arrays of 992 NbSi TES

•  -Capacity coupling-Time Domain Multiplexing

•  -Bias reversal AC SQ1 bias

•  -The current bias steps through the rows for a first

multiplexing stage and a cryogenic amplifier steps

through the columns for a second multiplexing stage

•  -This is done by the ASIC

•  -Multiplexing factor 128/1 in a 2D configuration


Forecast


Forecast


Summary•  QUBIC is a novel instrumental concept

!  Bolometric Interferometer optimized to handle systematics: QUBIC is a synthesized imager (or an imaging interferometer) observing a selected range of spatial frequencies that can be accurately calibrated

!  Dedicated to CMB polarimetry and inflationary physics

!  High sensitivity with ~2000 TES bolometers

!  Located at Dome C, Antarctica

!  Target :

- First module (150/220 GHz): r < 0.05 at 90% C.L. (first light late 2016)

- Six modules (90, 150, 220 GHz) : r < 0.01 at 90% C.L.

Documents

The QUBIC experiment